The tragic hero of Cassius warns readers to never underestimate the ambition of others and to always have some ambition themselves.
Readers care about Cassius because he is a senator, in the loop with Caesar, who even asks Cassius for help once. I choose an example of Cassius bragging about his 'in the loop' status and drew a sinking ship (HMS Caesar) next to the lifeboat of Cassius.
A major example of Cassius misunderstanding one's ambition is Brutus. I choose this example because it also touches on Cassius' flaw that he cannot see the lack of ambition in himself, even though the line references Brutus' own limitation. A picture of an eye trying to look through a broken mirror represents this idea.
Cassius' flaw begins to hurt him when Brutus outright defies Cassius' proposal for a group oath- he begins to take control from Cassius because he was underestimated. A cross through a pinky swear image represents this idea.
In his birthday speech, a Roman Civil War about to unfold before him, Cassius finally admits what he has known internally for a while- somewhere he went horribly wrong. A falling symbol of Rome (the eagle) represents this in words and the image.
He then realizes that if he had been ambitious and taken rule of Rome himself, things would have gone much better. Some audience members begin to sympathize with Cassius's honest mistake when he crys to Brutus in their argument. He alludes to the fact that he has lost everything he strived to achieve- greatness for Rome.